0 Assigned ID: 7487 ----- Attempting Submission 1 (Thu Apr 16 17:08:56 GMT 2026) ----- In 2017, a policy was enacted to protect Hubble's invaluable UV capability from permanent damage due to unintended exposure to bright M-dwarf flares. This essential protection has unavoidable consequences for science, effectively placing observations with sensitive instrument modes off-limits for bright or active M dwarfs, as well as poorly studied M dwarfs lacking the measurements required as input to the 2017 scheme. The impact extends beyond M dwarfs as well: any science target with a ``contaminating'' M dwarf within 5'' is subject to the 2017 restrictions. However, in the years since the policy was developed, HST has amassed a large body of data on M-dwarf UV activity, including hundreds of UV flare observations and robust activity-rotation relationships, enabling substantially more accurate predictions of M-dwarf flares across the UV band. These observations have exposed limitations of the 2017 policy that both unnecessarily prohibit safe observations -- such as those of nearly flare-immune Lyman-alpha -- and unwisely permit potentially hazardous observations, such as those using the COS/G130M/1222 mode, which incorporates flare-prone UV lines the policy does not address. The proposed effort will use the hundreds of M-dwarf UV measurements now available from HST archival data, along with updated statistical methods, to develop and publish a general tool that more accurately and comprehensively quantifies M-dwarf flare risks. This tool can be used to update HST's bright object protection policy, enhancing both science and safety, and will be applicable to any UV observatory, including Habitable Worlds. Dr. Pineda has extensive experience studying stellar magnetic activity, including flares. He has led multiple HST programs (e.g., 14640, 16197) targeting the UV emissions of M-dwarf stars, and measuring the rotation-activity correlations of the M-dwarf transition region emissions (e.g., Pineda et al. 2021). Dr. Pineda also an expert in statistical practices for probabilistic treatments of astrophysical data, relevant for the proposed risk framework. Dr. Loyd is a world expert in stellar UV observations, and exoplanet science leading multiple programs targeting M-dwarf UV emissions (Loyd et al. 2018ab, 2021) and exoplanet atmospheric escape (e.g., Loyd et al. 2023.) Dr. Loyd is the PI for the STELA HST multi-cycle treasury program survey 625 orbits (GO-17804). Stellar Physics and Stellar Types 0 false true false false false false false SUPPORTED